Investigating and imaging the liver and biliary tract

Abstract With an ever increasing range of investigative tools available for suspected liver or biliary tract disease, it is even more important that they are used rationally in the knowledge of their individual value. Conventional liver function tests are non-specific although the distinction between hepatitic and cholestatic patterns can be useful. Serum albumin and prothrombin time are the only routine liver ‘function' tests that reflect synthetic function of the liver. Isolated evaluations of γ-glutamyl transferase (γ-GT) suggest enzyme induction, particularly from alcohol misuse. When parenchymal liver disease is suspected, a range of blood tests is available to diagnose viral, metabolic and immune causes. Ultrasonography, inexpensive and widely available, is established as the first-line imaging investigation, and is excellent at detecting extrahepatic obstruction and space-occupying lesions, and spiral computed tomography is usually required to evaluate such findings further. Magnetic resonance imaging now provides excellent non-invasive computer reconstruction of the biliary and pancreatic ducts, and endoscopic ultrasound can help characterize small lesions in the pancreas or lower bile duct – these rapidly evolving techniques have rendered diagnostic endoscopic retrograde cholangiopancreatography (ERCP) unnecessary in most cases. Liver biopsy remains necessary for the confirmation of most diffuse parenchymal liver diseases if this necessary to guide further management. Taking the biopsy under ultrasound guidance is becoming common practice and avoids inadvertent puncture of other viscera. If the patient's clotting parameters preclude conventional biopsy, the track may be plugged or it may be performed by the transvenous, usually transjugular, or laparoscopic route.